1. Field
Exemplary embodiments relate to wireless communication, and more particularly, to a method and apparatus for executing PUSCH/PUCCH power control and/or power scaling in a power-limited state.
2. Description
In a wireless communication system, a User Equipment (UE) may execute wireless communication through two or more evolved NodeBs (eNB) from among eNBs forming at least one serving cell. This is an example of configuring dual connectivity with at least two nodes. In other words, the dual connectivity refers to an operation in which a UE that is in a Radio Resource Control (RRC) connected state with two or more different network points, consumes radio resources provided by the network points. Here, the at least two different network points may be a plurality of eNBs that are physically or logically distinguished from one another. One of them may be a Master eNB (MeNB) and the remaining eNBs may be Secondary eNBs (SeNB).
In the dual connectivity, each eNB transmits downlink data and receives uplink data, through a bearer configured for a UE. In this instance, a bearer may be configured through a single eNB, or two or more different eNBs. In addition, in the case of dual connectivity, at least one serving cell may be configured for each eNB, and each serving cell may operate in an activated or deactivated state. In this instance, a Primary (serving) Cell that may be configurable based on an existing Component Carrier Aggregation (CA), may be configured for the MeNB. Here, the CA is to effectively use small band segments, which binds a plurality of physically continuous or non-continuous bands in a frequency domain so as to provide an effect same as when an eNB uses a logically large band.
For a SeNB, only a Secondary (serving) Cell (SCell) may be configured. In at least one of the SCells of SeNBs, a Physical Uplink Control CHannel (PUCCH) which is a physical channel for transmitting uplink control information may be configured. A serving cell group that is provided by the MeNB is referred to as a Master Cell Group (MCG), and a serving cell group that is provided by the SeNB is referred to as a Secondary Cell Group (SCG).
An eNB may use power headroom information of a UE to effectively utilize resources of the UE. Power control technology is an essential technology for minimizing interference elements for effective distribution of resources in wireless communication and for reducing battery power consumption. When a UE provides power headroom information to an eNB, the eNB may estimate an uplink maximum transmission power {circumflex over (P)}CMAX(i) that may be allocated to the UE. Therefore, the eNB may provide the UE with uplink scheduling such as Transmit Power Control (TPC), Modulation and Coding Scheme (MCS), a bandwidth, or the like, within the range of the estimated uplink maximum transmission power.
Unlike the assumption in the existing Long Term Evolution (LTE) system, when dual connectivity is configured for a UE, the UE may connect to at least two eNBs having independent schedulers, and transmit and receive data. Therefore, there is a desire for a new transmission power control method for a UE due to a difference in physical channel properties between a UE and a plurality of eNBs that the UE connects to (for example, a pathloss), a different Quality of Service (QoS), a dual connectivity mode (for example, 1A/3C), independent schedulers of the plurality of eNBs, or the like. Particularly, power of a UE in dual connectivity may be limited (for example, a total transmit power of a UE may exceed {circumflex over (P)}CMAX(i)). Under the above situation, there is a desire for a power scaling scheme for a UE to execute uplink transmission to a plurality of eNBs through a plurality of uplink channels in a single subframe.
The above information disclosed in this Background section is only for enhancement of understanding of the background of the inventive concept and therefore it may contain information that does not form any part of the prior art nor what the prior art may suggest to a person of ordinary skill in the art.